1. Filed of the Invention
This invention relates to an ophthalmic phototaking apparatus for effecting the recording and display of the image of an eye to be examined.
2. Related Background Art
As an eye fundus camera, there is known a system in which the image of an eye to be examined is picked up by a continuously light emitting light source, such as a halogen lamp, and the alignment with the eye to be examined or the observation of a region to be phototaken is effected by the use of an optical finder or a television monitor and an examiner pushes a switch to make a strobe emit light to thereby record the image of the fundus of the eye on silver salt film.
Also, in recent years, recording media have been made electronic by the development of electronic image art and there have been widely used a system in which, as is conventional, observation is effected by an optical finder or a television camera for exclusive use and recording is effected with an examiner's switch being recognized, a light source made to emit light, and a television signal, which is outputted from the television camera exclusively for recording on an analog recording device, such as a magnetic tape or still video and the reproduced image thereof is displayed on a television monitor, and a system in which a television signal is A/D-converted and an image is stored in a memory device, such as a frame memory and is again D/A-converted into a television signal, which is then displayed on a television monitor.
Particularly, among systems characterized by a high quality image, there is one in which for phototaking, a digital output is possible from a high resolution image pickup element used exclusively for still pictures, and this system is designed such that observation is effected by a television camera for exclusive use or an optical finder and image recording is effected with a digital output from the camera transferred to a discrete personal computer through an interface such as SCSI or PCMCIA, and thereafter displayed by software for recording/image display.
However, in the above-described eye fundus camera wherein recording is effected on an electronic recording medium, two optical systems and two television cameras become necessary, such as an optical finder or a television camera for observation and a television camera for recording or an image pickup element exclusively for still pictures, and this leads to a high cost. Particularly, in an apparatus wherein as in non-mydriatic eye fundus phototaking, observation is effected by infrared light and color phototaking is effected by visible light, an infrared television camera for observation and a color camera for phototaking become necessary, and even if use is made of an expensive three-plate type color camera to make the most of the resolving power of a television signal for phototaking, a television signal band is limited in a generally used television signal and there is a limit to the resolving power obtained.
There is also an eye fundus camera using a digital camera containing therein an A/D converter in which the number of pixels of an image pickup element is great and which can provide a highly minute image, and this is exclusively used for still pictures in the relation of transfer time for data, and cannot display an animated picture at a frame rate required during observation. Accordingly, during observation, a television camera and an optical finder exclusively for observation become discretely necessary.
Also, to display the still pictures of these discretely from this, it is necessary to transfer data to a personal computer or a work station through an interface such as SCSI or PCMCIA contained in the camera, and display the data on a display for the computer by software for exclusive use, and to see the phototaken data, there is the problem that a large computer and a monitor must be installed near the apparatus.